senior administration officials tell me president obama will continue to be briefed on this situation throughout the evening. right now, the white house is approaching this as an act of terror. i can read you the latest statement that we have from a senior administration official, rachel. i believe we have a graphic of that as well. this is according to an official who says, "any event with multiple explosive devices as this appears to be is clearly an act of terror and will be approached as an act of terror. however, we don't yet know who carried out this attack and a thorough investigation will have to determine whether it was planned and carried out by a terrorist group, foreign or domestic." now, i can tell you, rachel, that is really the key question here tonight. was this carried out by a terrorist group homegrown, or a foreign terrorist group? and, rachel, the white house just simply does not know. i've heard you sort of discussing this as well. there's still a lot of questions about who is responsible for what happened today in boston. the president was made aware of the event